Deletes a Playwright test app and cascades all its tenants/users. Refuses reserved domains (NBLOCKS_DASHBOARD, SDK_APP, BRIDGE_NEXTJS_TEST_DASHBOARD). Intended for worker-scoped fixture teardown: each parallel Playwright worker creates its own isolated app via setup-test-app, then deletes it here when the worker finishes. DELETE /account/test/playwright/test-app Headers: x-playwright-api-key: <your-api-key> Body: { domain: string }